Automation of machining and like operations frequently involves use of gantry machines, robots, and like positioning apparatus fitted with sophisticated drilling and other rotary tool equipment. These positioning apparatus that can be fitted with self-contained machining units to perform certain tasks such as drilling, counter-sinking, tapping, facing, reaming, grooving, and similar operations. Frequently, there is a need to change the tool being used by the machining unit as it progressively machines a workpiece. For example, drills of different diameters or other geometries are often required to produce the desired features on a workpiece.
It is desirable to perform tool changing automatically with commands which can be conveniently programmed into the machine controller operating the robot or other positioning apparatus. However, the instrumentalities needed to effectuate reliable automatic tool gripping and releasing action may not be readily adoptable or even apparent. Further, it is important that any tool changing feature not unnecessarily add, for example, to the cost, complexity, bulk, and mass of the system.